Method and apparatus for forming heat exchange fin collars

ABSTRACT

Conjoint flanging, ironing and pinch-trimming fabrication of integral collars from metal sheet material, e.g. relatively thin work hardened aluminum alloy sheet material, having an aperture overlying a female die assembly of a coaxially arranged flanging and ironing die section and pinch-trim die section, said pinchtrim die section being disposed in predetermined spaced relation with said flanging and ironing die section and having a transverse shoulder contiguously connecting said die sections at the juncture therebetween, the axial position of the shoulder defining the height of the collar to be fabricated, by moving a selectively shaped male plunger having an enlarged sheet engaging portion through said sheet aperture and into operative relation with said female die sections to gradually and incrementally flange and iron the portions of said sheet material disposed about said aperture therein to form an extending collar of reduced wall thickness, and to sequentially force the deformed sheet material at said juncture against said shoulder to pinchtrim excess portions of the flanged and ironed sheet material to provide such reduced wall thickness collar with a uniform height and a well-defined collar edge.

[451 Aug. 8, 1972 METHOD AND APPARATUS FOR FORMING HEAT EXCHANGE FIN COLLARS [72] Inventors: Roger C. Haddon, Monroeville; Colin H. Kilgore, New Kensington, both of Pa.

[73] Assignee: Aluminum Company of America,

Pittsburgh, Pa.

[22] Filed: Sept. 28, 1970 [21] Appl. No.: 75,805

[52] US. Cl. ..113/1 C, 113/118 C, 72/334, 72/348 [51] Int. Cl. ..B2ld 53/02 [58] Field of Search ..113/118 C, l C; 29/DIG. 9, 29/DIG. 11; 72/333, 325, 334, 335, 340, 348

[56] References Cited UNITED STATES PATENTS 3,131,758 5/1964 Kemetal. ..113/118C 368,821 8/1887 Edmands ..29/DIG. 9 1,173,793 2/1916 George ..72/348 1,370,116 3/1921 Johnson ..72/347 580,845 4/1897 Buxton ..113/118 C 2,977,918 4/1961 Kritzer ..113/118 C 2,383,584 8/1945 Beishline et al. ..72/335 FOREIGN PATENTS OR APPLICATIONS 98,686 8/ 1898 Germany ..72/334 Primary Examiner-Richard J. Herbst Att0rney--R0bert E. lsner and Peter J. Franco Conjoint flanging, ironing and pinch-trimming fabrication of integral collars from metal sheet material, eg relatively thin work hardened aluminum alloy sheet material, having an aperture overlying a female die as sembly of a coaxially arranged flanging and ironing die section and pinch-trim die section, said pinch-trim die section being disposed in predetermined spaced relation with said flanging and ironing die section and having a transverse shoulder contiguously connecting said die sections at the juncture therebetween, the axial position of the shoulder defining the height of the collar to be fabricated, by moving a selectively shaped male plunger having an enlarged sheet engaging portion through said sheet aperture and into operative relation with said female die sections to gradually and incrementally flange and iron the portions of said sheet material disposed about said aperture therein to form an extending collar of reduced wall thickness, and to sequentially force the deformed sheet material at said juncture against said shoulder to pinch-trim excess portions of the flanged and ironed sheet material to provide such reduced wall thickness collar with a uniform height and a well-defined collar edge.

18 Claims, 3 Drawing figures PATENTEDAUB 8 m2 AWIIIIIIIEFEZ NTORS C HADDON KILGORE BY Z ATTORNEY METHOD AND APPARATUS FOR FORMING HEAT EXCHANGE FIN COLLARS The present invention relates to the improved fabrication of integral collars from metal sheet material, e. g. relatively thin work hardened aluminum alloy sheet material, and more particularly to an apparatus and method for forming integral extending cylindrically shaped collars of uniform collar height, e.g. heat exchanger fin collars, from such material in a conjoint single station operation.

The pinch-trimming of a cup or the like at the end of a drawing operation is conventional but this expedient involves a specialized technique of limited application. The production of cylindrical flanges and collars of pronounced structural thickness in forming presses is also known although the conventional apparatus and procedures used are not particularly appropriate in the case of collars of reduced structural thickness, especially from those made from relatively thin work hardened metal sheet material.

The formation of such integral extending collars in aluminum alloy sheet material is desirably included, for example, in the fabrication procedures for collar type heat exchanger fins. Present forming practices for heat exchanger fins effect such integral collar formation by incremental stretching of aluminum alloy having high tensile elongation values through a number of discrete forming operations. Alloys having tensile elongation values of 20% or more are usually required and as many as six to separate operations on annealed material are oftentimes required to produce satisfactory collar heights.

It is desirable for aluminum alloy sheet from which integral extending collars are formed to have relatively high yield strengths so that the unformed fins as well as the collars formed from such material, will not be readily damaged by accidental contact with other objects. This is particularly true with relatively thin fin stock material. With the methods heretofore known,

however, it has been difficult or impossible to form such collars in desired dimensions from thin work hardened sheet without splitting the collars. In fact, integral extending collars have typically been formed from sheets of annealed material of high elongation in order to facilitate forming and avoid splitting the collars, yet provide resistance to damage. Accordingly, it is desirable to provide a method of forming integral extending collars from work hardened material so that thinner material can be utilized with adequate resistance to damage. it is also desired to provide a method of forming such collars from work hardened material to a height which has not previously been possible.

In copending US. application, Ser. No. 45,341, filed June 11, 1970, which is a continuation-in-part of US. application, Ser. No. 748,725, filed July 30, 1968, now abandoned, of overlapping inventorship herewith, there is disclosed and claimed a method for improved fabrication of integral collars of the instant heat exchanger fin type in which an apertured relatively thin work hardened aluminum alloy sheet material overlying an apertured female die is gradually and incrementally flanged and ironed by advancing a male plunger coaxially aligned with such apertures against the adjacent portions of the sheet material and into and through the female die. However, the collar height and collar edge resulting from such operations are not uniform and well-defined so that a separate pinch-trim station is necessary to trim off the end of the collar and provide the desired finally trimmed collar. Normally, in fabricating such fin collars, four separate forming stations are required; namely pierce, flange and iron, pinch-trim, and curl. The pierce station forms the necessary aperture in the sheet material, the flange and iron station forms the collar of reduced wall thickness, the pinch-trim station serves to trim off the end of the collar, and the curl station provides an outwardly diverging edge at the collar end.

It is an object of the present invention to conjointly effect the flange ironing and pinch trimming operations in the fabrication of integral extending collars, e.g. heat exchanger fin collars, from apertured, preferably relatively thin, metal sheet material, and to provide a composite die tool apparatus for this purpose.

It is another object of the invention to provide such an integral collar having a readily controllable, precise, consistent and uniform collar height, in one over-all forming operation rather than two, with the collar mouth having a resultant square edge configuration of enhanced desirability of subsequent curling at the curling station.

It is a further object of the invention to obviate the need for separate trimming of flanged edges, previously accomplished by machining, by employing instead a single over-all flange-iron and pinch-trim die tool operation.

Other and further objects of the invention will become apparent from the within specification and accompanying drawing, in which:

FIG 1 is a schematic view, partially in section, of a male plunger member and a female die assembly composed of a coaxially disposed flanging and ironing die section and pinch-trim die section representing a consolidated flange-iron and pinch-trim station illustrating the disposition of the various elements prior to flanging and ironing in accordance with one embodiment of the invention; I

FIG. 2 is a schematic enlarged partial view of the embodiment of FIG. 1 illustrating the pinch-trimming of the collar edge of an already flanged and ironed sheet material collar; and

FIG. 3 is a schematic enlarged view similar to that of FIG. 1 illustrating an axially adjustable pinch-trim die section with respect to the corresponding flanging and ironing die section to afford selective control of the collar height of the collar to be fabricated, in accordance with another embodiment of the invention.

in its broader aspects, the present invention relates to an improved apparatus and method for fabricating integral extending collars of selective uniform axial collar length by deforming metal sheet material, preferably relatively thin hard or intermediate temper aluminum sheet material, by unitary displacement of a selectively sized and shaped plunger through selectively sized coaligned apertures in the sheet material and an underlying female die assembly composed of a tandem arranged axially contiguous flanging and ironing die section and pinch-trim die section, to flange and iron incrementally and compositely the portions of the sheet material overlying the aperture of the flanging and ironing die section and to pinch-trim undesired excess of the flanged and ironed sheet material.

In its more specific aspects, the present invention provides an apparatus and method for fomiing collar type heat exchanger fins from relatively thin work consistent and uniform collar heights and outer edges 7 through provision of a novel female die combination comprising a flanging and ironing die section and an axially contiguous pinch-trim die section which cooperate with a suitably shaped and sized male plunger member having an enlarged sheet engaging portion that includes a selectively configured flanging, ironing and pinchtrimming peripheral edge. I

Advantageously, by way of the present invention, satisfactory flatness of the formed parts is obtained because of the limited locus of deformation thereof, as well as the minimization of damaged stock because of the permitted utilization of hard and intermediate temper materials, and the reduced tooling and maintenance costs attendant the reduced number of required operations. Controllable precise, consistent and uniform collar heights and outer edges are further more obtainable from given stock thicknesses through variation in the degree of ironing effected during the single deformation operation coupled with the pinchtrimming of the collar end at a selective axial point of the female die combination used.

Referring to the drawings, FIGS. 1 and 2 show an improved apparatus for carrying out the conjoint flanging, ironing and pinch-trimming fabrication of an integral extending collar of selective uniform axial collar length, i.e. height, from relatively thin work hardened aluminum alloy sheet material 1, such as hard or intermediate temper aluminum alloy sheet material, having a selectively shaped and sized aperture 2 therein, in accordance with the method of the present invention.

Mountedin top member 7 for axial movement in conjunction therewith in reciprocable male punch or plunger member 3 having an enlarged and selectively shaped sheet engaging portion 4 of uniformly and gradually increasing cross-sectional extent from base 5, diametrically sized to pass readily through aperture 2 in sheet material 1, to ironing bead or curved surface 6, of maximum diametric dimension less than that of the aperture defined by the bore of the flanging and ironing die section hereinafter described but greater than the difference between the diametric extent of such flanging and ironing die aperture and twice the thickness of the sheet material. The axial point of maximum crosssectional dimension at ironing bead 6 is selectively sized to define the interior cross-sectional dimension of the collar to be fabricated and conjointly serves as a pinch trimming peripheral edge 8.

A female die combination or assembly 9, composed of a flanging and ironing die section 10 and a coaxial and contiguous pinch-trim ring or die section 11, is situated operatively in tool block 12 below plunger member 3 and coaxially disposed in the path of advance of the plunger member. Flanging and ironing die section 10 is provided with a selectively shaped aperture l3, complemental to the cross-sectional shape of the sheet engaging portion 4, with such aperture being sized to define the exterior dimensional extent of such collar to be fabricated. Pinch-trim die section 11 is similarly provided with a selectively shaped aperture 14, complemental to that of aperture 13 and to the cross-sectional shape of sheet engaging portion 4 at said peripheral edge 8, with aperture 14 being sized to define the interior cross-sectional dimension of such collar. Pinch-trim die section 11 is disposed in predetermined spaced relation with flanging and ironing die section 10, for example by being receivably mounted in a recess 15 in the lower end of flanging and ironing die section 10. If desired, sections 10 and 11 can be integral, e.g. in one piece.

It is clear from FIG. 1 that apertures 13 and 14 are provided in contiguous coaxial alignment and in turn in coaxial alignment with the sheet engaging plunger portion 4. In this regard, pinch-trim die section 11 contains at the upper end thereof an inwardly extending transverse shoulder 16, extending from a juncture 17 formed with flanging and ironing die aperture 13 to a female pinch-trimming edge 18 defining the pinch-trim die aperture 14. Thus, the selective axial dimension of the flanging and ironing die aperture 13, e.g. from the rounded edge or lip 19 at the die entrance, to the juncture 17 with shoulder 16 defines the axial length of the collar to be fabricated (see distance H in FIG. 3), while the transverse dimension of shoulder 16 from the juncture 17 to the female pinch-trimming edge 18 defines the reduced thickness of the sheet material 1a (see FIG. 2) after flanging and ironing.

The upper peripheral edge 8 of plunger member 3 and lip 19 at the die entrance are suitably rounded to provide for gradual rather than abrupt dimensional transition whereas female pinch-trimming edge 18 presents a sharp cutting edge.

Upon coaxially aligning the complementally shaped aperture 2 in sheet material 1, interposed between plunger member 3 and die assembly 9, with the sheet engaging portion 4 and die apertures 13 and 14, such that sheet aperture 2 overlies flanging and ironing die aperture 13, plunger member 3 may be advanced sequentially along a reciprocal path from the position of non-engagement shown in FIG. 1 into and through flanging and ironing die aperture 13 and pinch-trim die aperture 14 to the operative engagement position shown in FIG. 2. During this advancement, the sheet engaging surfaces of the tapered portion 4 between base 5 and bulbous peripheral edge 8 will enter sheet aperture 2 and flange and iron incrementally and compositely the sheet material 1 surrounding sheet aperture 2 against the peripherally confining surface of flanging and ironing die aperture 13 to form the extending collar of reduced wall thickness 1a (FIG. 2). Upon continued displacement sequentially, the bulbous peripheral edge 8 will cuttingly coact with female pinch-trimming edge 18 while forcing the deformed sheet material constituting the terminal end portion of the extending collar at juncture 17 against shoulder 16 to cause the sheet material to occupy substantially completely the available space adjacent the shoulder and to pinch-trim the excess portion 1b of the flanged and ironed sheet material la. There is thus provided a uniform axial length, i.e. height, for the collar, yet to insure constant conditions, the shoulder 16, i.e. die section 11, should be maintained in selective fixed axial relation to flanging and ironing die sections in any position of movement of plunger member 3 and die assembly 9.

To keep sheet material 1 from lateral or transverse displacement during the deforming operation, the holddown pad 20 is carried beneath top member 7 above the sheet material and operatively adjacent the entrance of flanging and ironing die 10. Pad 20 is provided with aperture 21 defined therethrough in coaxial alignment with flanging and ironing die aperture 13 and plunger member 3 and dimensioned to receive plunger member 3 therethrough during the operative engagement movement of plunger member 3 into and through die assembly 9. Biasing means 22 and 23, e.g. springs, arranged operatively between top member 7 and pad 20, normally bias pad 20 toward die assembly 9 and cause pad 20 to be urged compressively against sheet material 1 overlying aperture 13 as top member 7 is downwardly moved to insert plunger member 3 into operative relation with die assembly 9.

Although in the usual instance the various parts will be of corresponding circular configuration, it will be realized that other appropriate cross-sectional shapes may also be utilized. In this regard, preferably sheet material aperture 2, die apertures 13 and 14, female pinch-trimming edge 18, pad aperture 21 and punch or plunger member 3 including sheet engaging portion.4 and bulbous peripheral edge 8 are of corresponding circular configuration whereas shoulder 16 is of corresponding annular cross-sectional configuration, e.g. from juncture 17 to pinch-trimming edge 18.

It is furthermore preferred to provide tapered sheet engaging portion 4 with sheet engaging surfaces, e.g. in the area from base 5 to ironing bead 6, disposed at an angle of about l0 to 30 to the longitudinal axis of plunger member 3, and more preferably with sheet engaging surfaces of truncated conical configuration. In accordance with the particular embodiment shown in FIG. 1, the sheet engaging surfaces are of truncated conical configuration having a vertex angle of about 10.

Thus, the integral extending collar of selective uniform collar length and thickness can be fabricated from metal sheet material, especially relatively thin work hardened aluminum alloy sheet material; by compositely flanging and ironing portions of the sheet material 1 surrounding the aperture 2 therein intermediate the moving selectively shaped plunger member 3 and the complementally shaped die section 10 to form an integral annular flange thereupon; deformably displacing the terminal end portion of the integral annular flange into compressive abutting relation with the selectively positioned stationary annulus or shoulder 16 aligned in the path of advance of the plunger member 3 by continued displacement of the plunger member; and serving excess sheet material lb from the terminal end of the flange disposed in abutting relation to the stationary annulus 16 by displacement of the plunger member 3 past the defining edge 18 of the stationary annulus l6.

Satisfactory results may be obtained in accordance with the invention even though initially sheet aperture 2 has a cross-sectional dimension at least equal to twothirds of that of flanging and ironing die aperture 13. Optimum results occur where initially such sheet aperture has a minimal cross-sectional dimension at least equal to three-fourths of that of the flanging and ironing die aperture. Thus, preferably the sheet aperture has a cross-sectional dimension equal to substantially from two-thirds to three-fourths of the corresponding die aperture of the flanging and ironing die section 10.

In the axially adjustable embodiment shown in FIG. 3, corresponding parts to those in FIGS. 1 and 2 are assigned corresponding prime reference numerals. In this instance, pinch-trim die section 11' in separate from flanging and ironing die section 10, being axially adjustably received in recess 15 in the lower end of die section 10 at the threaded connection 15' Upon rotation of pinch-trim die section 11 in recess 15', the axial relation of pinch-trim die section 11 with respect to flanging and ironing die section 10' can be varied, in turn varying the corresponding axial disposition of pinch-trim die aperture 14', shoulder 16', juncture 17 and female pinch-trimming edge 18' so as to change the axial length of flanging and ironing die aperture 13' which determines the height H of the collar to be fabricated.

Section 11 may be locked in axial position by any suitable means, e.g. by a retaining ring inserted in recess 15 via the threads of threaded connection 15 and compressively engaging the underside of section 11 in the conventional manner. This will prevent both rotational and axial displacement of section 11 with respect to section 10' and the plunger member in any position of movement of the plunger member and the die assembly. Hence, section 11 and shoulder 16' will be selectively positioned yet fixed or stationary during the overall operation.

In the same way, section 11 in the embodiment of FIGS. 1 and 2 may be locked in place by an appropriate retaining ring (not shown) in recess 15, provision being made at the lower end portion of recess for a threaded connection for such ring below section 11 as contemplated above for the retaining ring in the embodiment of FIG. 3.

It will be realized that the transverse dimension of the reduced thickness collar is determined by the corresponding selective distance from juncture 17 at shoulder 16' to female pinch-trimming edge 18 while the axial dimension of the extending collar is determined by the corresponding selective distance from shoulder 16 to the entrance of the flanging and ironing die aperture 13.

In accordance with a significant feature of the present invention, as can be appreciated from FIG. 2, the downward movement of plunger member 3 causes bulbous peripheral edge 8 of ironing bead 6 to force the sheet material downwardly against shoulder 16 and outwardly against the square comer formed at juncture 17, so that the flanged and ironed sheet material 1a of reduced thickness fills and occupies substantially completely the available space at such square comer. Moreover, the excess sheet material 1b is pinchtrimmed off at female pinch-trimming edge 18 by the downward cutting or shearing action of bulbous peripheral edge 8 thereat. The sheared off excess material 1b exits downwardly through the central bore of pinch-trim die section 11. In this way, the outer end or mouth of the collar is provided with a corresponding squared off edge at a precise, consistent and uniform axial point to provide the extending collar with a constant axial length or height. Of course, the axial point and in turn the axial length or height can be varied, i.e. selectively controlled, according to the embodiment of FIG. 3, yet the pinch-trim die section 11 including shoulder 16' and juncture 17' will remain fixed axially in relation to flanging and ironing die section in any position of movement of plunger member 3 and die assembly 9'.

From the foregoing, it will be appreciated that flang ing and ironing die aperture 13 or 13' and pinch-trim die aperture 14 or 14' will be in contiguous coaxial alignment in tandem, i.e. the axial point of termination of aperture 13 or 13 will coincide with the axial point of beginning of aperture 14 or 14. This point of axial coincidence is determined by the corresponding axial position of surface 16 or 16' and is defined axially by juncture 17 or 17'. Preferably, shoulder 16. or 16 will extend normally to the longitudinal axis of the die as sembly so that female pinch-trimming edge 18 or 18' will lie in the transverse plane of shoulder 16 or 16 intersecting, die apertures 13, 14 or 13, 14 at juncture 17 or 17'. This configuration will provide a right angle corner at the juncture of flanging and ironing die aperture 13 or 13' and shoulder 16 or 16' which in conjunction with the disposition of bulbous peripheral edge 8 at female pinchtrimming edge 18 or 18 will permit the outer end of the collar being fabricated to have a squared off or flat edge (see FIG. 2).

Hence, the pinch-trimming action is accomplished by the maximum cross-sectional dimension, e.g. radius, of the plunger member which squeezes the flanged and ironed sheet material against the sharp female pinchtrim edge of the pinch-trim die section inserted in the aperture of the flanging and ironing die section. Generally, the clearance between the maximum crosssectional dimension, e.g. diameter, of the bulbous peripheral edge of the plunger member and the female pinch-trimming edge of the pinch-trim die section is kept to an absolute minimum for best results, and such clearance is preferably about 0.0002 inches per side.

Advantageously, by way of the apparatus and method of the present invention, the problem of locating the formed collar over the separate station pinchtrim die is eliminated, yet the collar produced herein has not only a consistent collar height but also a square edge at the collar mouth or outer end since the ironing forces cause the sheet material to flow into the square comer between the flanging and ironing die section and the pinch-trim die section. This square edge will constitute a better edge for curling at the subsequent curling station whereby to flare the mouth of the depending collar to the required diameter and contour.

It will be realized, of course, by the artisan that the instant apparatus can also be used to manufacture other types of flanged articles by employing the conjoint flanging ironing and pinch-trimming technique of the present invention, whereby the usual separate operation of trimming of the flanged article by machining can be eliminated.

With respect to temper, the method of the invention can be utilized advantageously in the fabrication of integral extending collars from work hardened aluminum alloy sheet of either hard or intermediate temper. Intermediate temper aluminum alloy materials such as 7072-Hl4, 3003-Hl2 and H14, and llO0-Hl4 have substantially higher yield strengths than do fully annealed or 0 temper materials, and will provide high strength fin stock even in thin sheet form, e.g. sheet material 0.003 inch to 0.020 inch in thickness. For example, 3003Hl2, an intermediate temper aluminum alloy product resulting from cold reduction of approximately 20 percent of the thickness of an annealed stock, has a typical yield strength of 18,000 pounds per square inch (psi) as compared to 6,000 psi yield strength for annealed material (3003-0), and 27,000 psi for full hard material (3003-Hl8). Data provided by the Aluminum Association indicates that for wrought products, the yield strength for one-quarter hard aluminum alloy product will be at least one-half the yield strength for the same alloy product in a full hard condition, and two or more times the typical yield strength for the product in a fully annealed or recrystallized condition. Intermediate temper products are, therefore, sufficiently hard to produce high strength fins, and yet may be formed into relatively high substantially split-free integral extending collars when fabricated by the method of the present invention. However, such products have generally been considered to be too hard to have been formed into such fin collars by the methods heretofore known, and could not be formed to the precise collar heights that are made possible by the method of the present invention.

Based on the foregoing, it seems apparent that the subject invention has appreciable utility employing various types of aluminum alloy materials of thicknesses varying from 0.003 up to, for example, about 0.020 and for hard and intermediate tempers, e.g. having yield strengths at least one-half the yield strength of the same material in a full hard condition. It is likewise apparent that while the subject invention has marked utility in the formation of cylindrically shaped collars from circularly shaped apertures, the conjoint operation of incremental and composite flanging and ironing as well as pinch-trimming may be utilized to produce high collars of consistent height around openings that depart, at least in some degree, from the circular openings specifically described herein.

As will be appreciated from the foregoing, practice of the herein described invention provides for the production, by a single conjoint over-all operation on relatively thin work hardened aluminum alloy sheet, of an improved product possessing, inter alia, markedly higher ratios of flange height to hole diameter than have been heretofore obtainable as well as uniform predetermined configuration collar outer edges. Such increase in collar length is directly attributable to the herein attainable effecting of reductions in wall thickness of up to and over 60 percent, as well over the value of about 35 40 percent that is recommended for conventional ironing operations.

It will be appreciated that the instant specification and drawings are set forth by way of illustration and not limitation, and that various modifications and changes may be made without departing from the spirit and scope of the present invention which is to be limited only by the scope of the appended claims.

What is claimed is:

1. Apparatus for fabricating integral extending collars of selective uniform axial collar length from metal sheet material which comprises a reciprocable male plunger member having a selectively shaped sheet engaging portion of unifomily and gradually increasing cross-sectional extent and of maximum cross-sectional dimension sized to define the interior cross-sectional dimension of such collar and forming at the point of maximum cross-sectional dimension a pinch-trimming peripheral edge, and I a female die assembly including a flanging and ironing die section coaxially disposed in the path of advance of said plunger member having a complementally shaped aperture sized to define the exterior dimensional extent of such collar and a coaxially disposed contiguous pinch-trim die section having a complementally shaped aperture sized to define the interior cross-sectional dimension of such collar, said pinch-trim die section having a transverse shoulder inwardly extending from a juncture formed with said flanging and ironing die aperture to a female pinch-trimming edge defining such pinch-trim die aperture, the axial dimension of said flanging and ironing die aperture to said juncture with said shoulder defining the axial length of such collar and the transverse dimension of said shoulder from said juncture to said female pinch-trimming edge defining the reduced thickness of the sheet material after flanging and ironing,

said plunger member and die assembly being arranged to receive interposed therebetween a metal sheet material having a corresponding complementally shaped aperture therein overlying said flanging and ironing die aperture and coaxially aligned with said sheet engaging portion of said plunger member and said die apertures, and

said plunger member being displaceable into operative engagement with said die assembly for incrementally and compositely flanging and ironing the sheet -material surrounding the sheet aperture between said sheet engaging portion of said plunger member and said flanging and ironing die aperture to form an extending collar of reduced wall thickness having its terminal end portions occupying substantially completely the available space adjacent said shoulder and for pinchtrimming the excess portion of the flanged and ironed sheet material by cutting coaction between said peripheral edge of said plunger member and said female pinch-trimming edge to provide a uniform'axial length for such collar.

2. Apparatus according to claim 1 wherein said shoulder is disposed in selective fixed axial relation to said flanging and ironing die section in any position of movement of said plunger member and die assembly.

3. Apparatus according to claim 2 wherein said die apertures, female pinch-trimming edge and peripheral edge of said plunger member are of corresponding circular configuration, and said shoulder is of c'orrespondsection to vary the axial position of said juncture and shoulder in dependence upon the selective axial length of the collar to be fabricated.

5. Apparatus according to claim 3 wherein a holddown pad is disposed operatively adjacent said flanging and ironing die section and includes means defining an aperture therethrough in coaxial alignment with said flanging and ironing die aperture and said plunger member dimensioned to receive therethrough said plunger member during operative engagement of said plunger member with said die assembly, said holddown pad being normally biased toward said die assembly to hold in place such sheet material when interposed thereat.

6. Apparatus according to claim 3 wherein the sheet engaging surfaces of said sheet engaging portion of said plunger member are disposed at an angle of from about 10 to 30 relative to the longitudinal axis thereof.

7. Apparatus according to claim 3 wherein the sheet engaging surfaces of said sheet engaging portion of said plunger member are of truncated conical configuratron.

8. Apparatus according to claim 3 wherein the sheet engaging surfaces of said sheet engaging portion of said plunger member are of truncated conical configuration having a vertex angle of about 10 degrees.

9. In the method of fabrication of integral extending collars of selective uniform collar length and thickness from metal sheet material, the steps of compositely flanging and ironing portions of the sheet material surrounding an aperture therein intermediate a moving selectively shaped plunger member and complementally shaped die section to form an integral annular flange thereupon,

deformably displacing the terminal end portion of said integral annular flange into compressive abutting relation with a selectively positioned stationary annulus aligned in the path of advance of the plunger member by continued displacement of said plunger member while maintaining said plunger member substantially in line contact operative engagement with the adjacent portions of such flange, and

severing excess sheet material from the terminal end of said flange disposed in abutting relation to said stationary annulus by displacement of said plunger member correspondingly in said line contact engagement therewith past the defining edge of said stationary annulus.

10. Method according to claim 9 wherein the sheet aperture has a cross-sectional dimension equal to substantially from two-thirds to three-fourths of the corresponding die aperture of said flanging and ironing die section. I

11. Method according to claim 9 wherein said sheet material is relatively thin work hardened aluminum alloy sheet material which has a thickness in the range of 0.003 to 0.02 inches.

12. Method according to claim 9 wherein said sheet material is relatively thin work hardened aluminum alloy sheet material which has a yield strength at least one-half the yield strength the sheet material would have in a full hard condition.

13. Method according to claim 9 wherein the sheet engaging surfaces of said plunger member are disposed at an angle of from about to 30 relative to the longitudinal axis thereof.

14. Method according to claim 9 wherein the sheet engaging surfaces of said plunger member are of truncated conical configuration.

15. Method according to claim 9 wherein the sheet engaging surfaces of said plunger member are of truncated conical configuration having a vertex angle of about 10.

16. Method according to claim 9 wherein the sheet aperture, the corresponding die aperture of said flanging and ironing die section and the defining edge of said stationary annulus are of circular configuration, and the sheet engaging surfaces of said plunger member are of truncated conical configuration having a vertex angle of about 10.

17. Method according to claim 9 wherein the portions of the sheet material adjacent to said sheet aperture are held against transverse displacement during said steps.

18. Method of fabricating integral extending collars of selective uniform collar length and thickness from relatively thin work hardened aluminum alloy sheet material which comprises compositely flanging and ironing portions of relatively thin aluminum alloy sheet material surrounding an aperture therein to form an integral annular flange thereupon, by moving along a path of advance relatively axially with respect to each other into operative engagement a. a reciprocable male plunger member having a selectively shaped sheet engaging portion of uniformly and gradually "increasing cross-sectional extent and of maximum cross-sectional dimension sized to define the interior cross-sectional dimension of such collar and forming at the point of maximum cross-sectional dimension a pinch-trimming peripheral edge, and

b. a female die assembly including a flanging and ironing die section coaxially disposed in the path of advance having a complementally shaped aperture sized to define the exterior dimensional extent of such collar and a coaxially disposed contiguous pinch-trim die section having a complementally shaped aperture sized to define the interior cross-sectional dimension of such collar, said pinch-trim die section having a selectively positioned fixed transverse shoulder inwardly extending from a juncture formed with said flanging and-ironing die aperture to a female pinch-trimming edge defining said pinch-trim 4 die aperture, the axial dimension of said flanging and ironing die aperture to said juncture with said shoulder defining the axial length of such collar and the transverse dimension of said shoulder from said juncture to said female pinch-trimming edge defining the reduced thickness of the sheet material after flanging and ironing, while maintaining said sheet material interposed between said plunger member and die assembly with the sheet material aperture overlying said flanging and ironing die aperture and coaxially aligned with the sheet engaging portion of said 1 rmembe d aid diea rtures aid shee hi e al apertu re eing corn ementall y shape deformably displacing the terminal end portion of said integral annular flange into compressive abutting relation with said transverse shoulder aligned in the path of advance by continued relative axial movement of said plunger member and die assembly to form an extending collar of reduced wall thickness having its terminal end portion occupying substantially completely the available space adjacent said shoulder, and

severing excess sheet material from the terminal end of said flange disposed in abutting relation to said transverse shoulder by further relative axial movement of said plunger member and die assembly until said peripheral edge of said plunger member passes said female pinch-trimming edge to provide a uniform axial length for such collar. 

1. Apparatus for fabricating integral extending collars of selective uniform axial collar length from metal sheet material which comprises a reciprocable male plunger member having a selectively shaped sheet engaging portion of uniformly and gradually increasing cross-sectional extent and of maximum cross-sectional dimension sized to define the interior cross-sectional dimension of such collar and forming at the point of maximum cross-sectional dimension a pinch-trimming peripheral edge, and a female die assembly including a flanging and ironing die section coaxially disposed in the path of advance of said plunger member having a complementally shaped aperture sized to define the exterior dimensional extent of such collar and a coaxially disposed contiguous pinch-trim die section having a complementally shaped aperture sized to define the interior cross-sectional dimension of such collar, said pinch-trim die section having a transverse shoulder inwardly extending from a juncture formed with said flanging and ironing die aperture to a female pinch-trimming edge defining such pinch-trim die aperture, the axial dimension of said flanging and ironing die aperture to said juncture with said shoulder defining the axial length of such collar and the transverse dimension of said shoulder from said juncture to said female pinch-trimming edge defining the reduced thickness of the sheet material after flanging and ironing, said plunger member and die assembly being arranged to receive interposed therebetween a metal sheet material having a corresponding complementally shaped aperture therein overlying said flanging and ironing die aperture and coaxially aligned with said sheet engaging portion of said plunger member and said die apertures, and said plunger member being displaceable into operative engagement with said die assembly for incrementally and compositely flanging and ironing the sheet material surrounding the sheet aperture between said sheet engaging portion of said plunger member and said flanging and ironing die aperture to form an extending collar of reduced wall thickness having its terminal end portions occupying substantially completely the available space adjacent said shoulder and for pinch-trimming the excess portion of the flanged and ironed sheet material by cutting coaction between said peripheral edge of said plunger member and said female pinch-trimming edge to provide a uniform axial length for such collar.
 2. Apparatus according to claim 1 wherein said shoulder is disposed in selective fixed axial relation to said flanging and ironing die section in any position of movement of said plunger member and die assembly.
 3. Apparatus according to claim 2 wherein said die apertures, female pinch-trimming edge and peripheral edge of said plunger member are of corresponding circular configuration, and said shoulder is of corresponding annular cross-sectional configuration.
 4. Apparatus according to claim 3 wherein said pinch-trim die section is separate from and axially adjustable with respect to said flanging and ironing die section to vary the axial position of said juncture and shoulder in dependence upon the selective axial length of the collar to be fabricated.
 5. Apparatus according to claim 3 wherein a hold-down pad is disposed operatively adjacent said flanging and ironing die section and includes means defining an aperture therethrough in coaxial alignment with said flanging and ironing die aperture and said plunger member dimensioned to receive therethrough said plunger member during operative engagement of said plunger member with said die assembly, said hold-down pad being normally biased toward said die assembly to hold in place such sheet material when interposed thereat.
 6. Apparatus according to claim 3 wherein the sheet engaging surfaces of said sheet engaging portion of said plunger member are disposed at an angle of from about 10* to 30* relative to the longitudinal axis thereof.
 7. Apparatus according to claim 3 wherein the sheet engaging surfaces of said sheet engaging portion of said plunger member are of truncated conical configuration.
 8. Apparatus according to claim 3 wherein the sheet engaging surfaces of said sheet engaging portion of said plunger member are of truncated conical configuration having a vertex angle of about 10 degrees.
 9. In the method of fabrication of integral extending collars of selective uniform collar length and thickness from metal sheet material, the steps of compositely flanging and ironing portions of the sheet material surrounding an aperture therein intermediate a moving selectively shaped plunger member and complementally shaped die section to form an integral annular flange thereupon, deformably displacing the terminal end portion of said integral annular flange into compressive abutting relation with a selectively positioned stationary annulus aligned in the path of advance of the plunger member by continued displacement of said plunger member while maintaining said plunger member substantially in line contact operative engagement with the adjacent portions of such flange, and severing excess sheet material from the terminal end of said flange disposed in abutting relation to said stationary annulus by displacement of said plunger member correspondingly in said line contact engagement therewith past the defining edge of said stationary annulus.
 10. Method according to claim 9 wherein the sheet aperture has a cross-sectional dimension equal to substantially from two-thirds to three-fourths of the corresponding die aperture of said flanging and ironing die section.
 11. Method according to claim 9 wherein said sheet material is relatively thin work hardened aluminum alloy sheet material which has a thickness in the range of 0.003 to 0.02 inches.
 12. Method according to claim 9 wherein said sheet material is relatively thin work hardened aluminum alloy sheet material which has a yield strength at least one-half the yield strength the sheet material would have in a full hard condition.
 13. Method according to claim 9 wherein the sheet engaging surfaces of said plunger member are disposed at an angle of from about 10* to 30* relative to the longitudinal axis thereof.
 14. Method according to claim 9 wherein the sheet engaging surfaces of said plunger member are of truncated conical configuration.
 15. Method according to claim 9 wherein the sheet engaging surfaces of said plunger member are of truncated coniCal configuration having a vertex angle of about 10*.
 16. Method according to claim 9 wherein the sheet aperture, the corresponding die aperture of said flanging and ironing die section and the defining edge of said stationary annulus are of circular configuration, and the sheet engaging surfaces of said plunger member are of truncated conical configuration having a vertex angle of about 10*.
 17. Method according to claim 9 wherein the portions of the sheet material adjacent to said sheet aperture are held against transverse displacement during said steps.
 18. Method of fabricating integral extending collars of selective uniform collar length and thickness from relatively thin work hardened aluminum alloy sheet material which comprises compositely flanging and ironing portions of relatively thin aluminum alloy sheet material surrounding an aperture therein to form an integral annular flange thereupon, by moving along a path of advance relatively axially with respect to each other into operative engagement a. a reciprocable male plunger member having a selectively shaped sheet engaging portion of uniformly and gradually increasing cross-sectional extent and of maximum cross-sectional dimension sized to define the interior cross-sectional dimension of such collar and forming at the point of maximum cross-sectional dimension a pinch-trimming peripheral edge, and b. a female die assembly including a flanging and ironing die section coaxially disposed in the path of advance having a complementally shaped aperture sized to define the exterior dimensional extent of such collar and a coaxially disposed contiguous pinch-trim die section having a complementally shaped aperture sized to define the interior cross-sectional dimension of such collar, said pinch-trim die section having a selectively positioned fixed transverse shoulder inwardly extending from a juncture formed with said flanging and ironing die aperture to a female pinch-trimming edge defining said pinch-trim die aperture, the axial dimension of said flanging and ironing die aperture to said juncture with said shoulder defining the axial length of such collar and the transverse dimension of said shoulder from said juncture to said female pinch-trimming edge defining the reduced thickness of the sheet material after flanging and ironing, while maintaining said sheet material interposed between said plunger member and die assembly with the sheet material aperture overlying said flanging and ironing die aperture and coaxially aligned with the sheet engaging portion of said plunger member and said die apertures, said sheet material aperture being complementally shaped and sized to have a minimal cross-sectional dimension at least equal to two-thirds of that of said flanging and ironing die aperture, deformably displacing the terminal end portion of said integral annular flange into compressive abutting relation with said transverse shoulder aligned in the path of advance by continued relative axial movement of said plunger member and die assembly to form an extending collar of reduced wall thickness having its terminal end portion occupying substantially completely the available space adjacent said shoulder, and severing excess sheet material from the terminal end of said flange disposed in abutting relation to said transverse shoulder by further relative axial movement of said plunger member and die assembly until said peripheral edge of said plunger member passes said female pinch-trimming edge to provide a uniform axial length for such collar. 